Control of Ventilation Flashcards
Central controllers of the respiratory control system
Pons, medulla, other parts of the brain
Respiratory effectors
Diaphragm
Intercostal muscles
Sternocleidomastoids
Scalene muscles
Abdominals
Nasopharyngeal muscles
Sensors of the respiratory control system
Central and peripheral oxygen and chemoreceptors
Breathing can be voluntarily controlled from the ____ along w input from the __ and __
cerebral cortex
limbic system & hypothalamus
Brainstem respiratory controls
Medulla respiratory center
Apneustic center
Pneumotaxic center in the upper pons
Diving reflex
Heart rate slows when you immerse your face in cold water and hold your breath
This preferentially distributes O2 stores to the heart and brain to allow staying underwater for longer.
The diving reflex can be used to break
supraventricular tachycardia
(because it slows the heart down; very strong in babies)
What respiratory variable can cross the bloodbrain barrier and stimulate central chemoreceptors?
CO2
(O2 does cross, but there is no response to hypoxia in the central chemoreceptors)
Why are there more rapid changes in pH of CSF compared to blood?
There’s no hemoglobin.
So when CO2 reacts w H2O in cerebrospinal fluid, there is less buffering capacity.
What are the peripheral chemoreceptors?
How do they respond to changes in oxygen?
What factors change the sensitivity of peripheral chemoreceptors?
- Glomus cells, type I and II
- Non-linear response to low O2, responds maximally when pO2 is less than 50
- Increased CO2 & acidic conditions (increased H+) increases the response
List the lung receptors that provide sensory input to the breathing centers
- Stretch receptors: smooth muscle cells send input to brain via vagus nerve
- Irritant receptors between airway epithelial cells
- Pulmonary J receptors: juxtacapillary, in the alveolar walls
- Bronchial C fibers: stimulates bronchoconstriction and mucus secretion
What are the non-pulmonary receptors that provide sensory input to breathign centers?
-
Irritant receptors in the nose and upper airway
- Induces coughing & sneezing
- Joint & muscle receptors: stimulates respiratory increase in exercise
- Gamma system of stretch receptors: in the intercostals; controls strength of contraction
-
Arterial baroreceptors:
- increase ventilation when low bp
- decrease ventilation when hypertension
- Increased pain & temp increases ventilation
What is the most important stimulus to ventilation usually?
The central ventilatory response is magnified if the ____ level is low.
Arterial CO
Central ventilatory response is magnified if the arterial O2 is low
Most of the stimulus to breathe coems from the __ chemoreceptors, but the ___ chemoreceptors’ response is faster
Most = central
Faster = peripheral
What will DECREASE ventilatory response to CO2?
- Sleep, age genetics, racial diferences, personality, athletic fitness, perceived work of breathing
- Benzodiazepines and opioids
Metabolic acidosis ___creases the ventilation response to CO2
Metabolic acidosis causes the body to push the equation to the left –> ventilation increases –> lowers blood pCO2
It increases the response to carbon dioxide
Describe the changes in ventilation, blood CO2, and O2 that occur with normal vs intense exercise?
Dramatic increase in ventilation
- Normal exercise - arterial pO2, pCO2, and pH normal
- Intense exercise
- Arterial pCO2 falls
- Alveolar pO2 rises (bc above), arterial pO2 falls
- pH falls slightly due to lactic acidosis
Cheyne-Strokes respiration
10-20 second periods of apnea followed by equal periods of hyperventilation when the tidal volume gradually waxes and then wanes
Occurs during sleep, high altitudes, heart failure, brain disease/ injury
How does heart failure cause Cheyne-STrokes respiration?
How does stroke or brain injury do it?
Heart failure: delay in the feedback loop between blood carbon dioxide level, the brain, and the respiratory effector muscles due to decreased cardiac output
Stroke or brain injury: an injury to the central respiratory controllers in the brainstem.
